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General Biology 2
Quarter 4: Module 1-4

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 Republic of the Philippines
Department of Education
N a t i o n a l C a pi t a l Re g i o n
Sc h o o l s D i v i s i o n O f f i c e o f La s Pi ñ a s C i t y

DEVELOPMENT TEAM OF THE MODULE

WRITERS: JUIE ANDREA P. AÑANO, Master Teacher I
AYRA PATRICIA S. ALVERO, Teacher III
AILINE C. AUSTRIA, Teacher III
LOUISE A. FERRER, Master Teacher I
CHRISTIAN MARU G. GARCIA, Teacher III
MARGIAN ERICA S. TAGUAS, Special Science Teacher I

CONSOLIDATOR: AYRA PATRICIA S. ALVERO, Teacher III

LANGUAGE EDITOR: IZAH RIZZA T. FRANCISCO, Teacher II

CONTENT EFREN M. LEYSAN JR., Teacher III
VALIDATORS: JOSELITO P. GRANDE JR., Teacher II
JOVILYN G. ENOLPE, Teacher I

COVER PAGE AIRA MARI CON M. AUSTERO

ILLUSTRATOR:

TEAM LEADER: DR. RAQUEL M. AUSTERO

Education Program Supervisor

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 Module 1 Plant Structure, Reproduction and Development

Most Essential Learning Competencies

• Compare and contrast the following processes in plants and animals:
reproduction, development, nutrition, gas exchange, transport/circulation,
regulation of body fluids, chemical and nervous control, immune systems and
sensory and motor mechanisms. (STEM_BIO11/12IVa-h-1)

What’s In
PLANT STRUCTURE, REPRODUCTION AND DEVELOPMENT

Plants, like multicellular animals, have organs that are composed of different
tissues, and tissues are composed of different cell types. Vascular plants have three basic
organs: roots, stems, and leaves. The basic morphology of vascular plants reflects their
evolutionary history as terrestrial
organisms that inhabit and draw
resources from two very different
environments. A root is an organ
that anchors a vascular plant in
the soil, absorbs minerals and
water, and stores food. Most
eudicots and gymnosperms have
a taproot system, consisting of
one large vertical root (the
taproot) that produces many small
lateral, or branch, roots. In
angiosperms, taproots often
store food that supports flowering
and fruit production later.
Seedless vascular plants and
most monocots, including
grasses, have fibrous root Figure 1a: Alternation Generation of Plants
Source:
systems consisting of a mat of https://www.google.com/search?q=alternation+of+generations+in+plants
thin roots that spread out below
the soil surface. A fibrous root system is usually shallower than a taproot system. Grass
roots are concentrated in the upper few centimeters of soil. As a result, grasses make
excellent ground cover for preventing erosion. Root hairs are extensions of individual
epidermal cells on the root surface. Absorption of water and minerals is also increased
by mutualistic relationships between plant roots and bacteria and fungi. Some plants have

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modified roots. Some arise from roots while adventitious roots arise aboveground from
stems or even from leaves. Some modified roots provide additional support and
anchorage. Others store water and nutrients or absorb oxygen or water from the air. A
stem is an organ consisting of alternating nodes, the points at which leaves are attached,
and internodes, the stem segments between nodes. At the angle formed by each leaf and
the stem is an axillary bud with the potential to form a lateral shoot or branch. The
presence of a terminal bud is partly responsible for inhibiting the growth of axillary buds,
a phenomenon called apical dominance. Modified shoots with diverse functions have
evolved in many plants. These shoots, which include stolons, rhizomes, tubers, and
bulbs, are often mistaken for roots. Leaves are the main photosynthetic organs of most
plants, although green stems are also photosynthetic. While leaves vary extensively in
form, they generally consist of a flattened blade and a stalk, the petiole, which joins the
leaf to a stem node. Most monocots have parallel major veins that run the length of the
blade, while eudicot leaves have a multibranched network of major veins. Plant
taxonomists use floral morphology, leaf shape, spatial arrangement of leaves, and the
pattern of veins to help identify and classify plants.
Plants have evolved different reproductive strategies for the continuation of their
species. Some plants reproduce sexually while others reproduce asexually, in contrast
to animal species, which rely almost exclusively on sexual reproduction. Plant sexual
reproduction usually depends on pollinating agents, while asexual reproduction is
independent of these agents. Flowers are often the showiest or most strongly-scented
part of plants. With their bright colors, fragrances, and interesting shapes and sizes,
flowers attract insects, birds, and animals to serve their pollination needs. Other plants
pollinate via wind or water; still others self-pollinate. In gymnosperms, a leafy green
sporophyte generates cones containing male and female gametophytes; female cones
are bigger than male cones and are located higher up in the tree. For the sexual
reproduction in gymnosperm, male cone contains microsporophylls where male
gametophytes ( pollen ) are produced and are later carried by wind to female
gametophytes. The megaspore mother cell in the female cone divides by meiosis to
produce four haploid megaspores; one of the megaspores divides to form the female
gametophyte. The male gametophyte lands on the female cone, forming a pollen tube
through which the generative cell travels to meet the female gametophyte. One of the two
sperm cells released by the generative cell fuses with the egg, forming a diploid zygote
that divides to form the embryo. Unlike angiosperms, ovaries are absent in gymnosperms,
double fertilization does not take place, male and female gametophytes are present on
cones rather than flowers, and wind (not animals) drives pollination. Pollination, the
transfer of pollen from flower-to-flower in angiosperms or cone -to-cone in gymnosperms,
takes place through self-pollination or cross-pollination. Cross-pollination is the most
advantageous of the two types of pollination since it provides species with greater genetic
diversity. Maturation of pollen and ovaries at different times and heterostyly are methods

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plants have developed to avoid self-pollination. The placement of male and female
flowers on separate plants or different parts of the plant are also barriers to self-
pollination. Double fertilization involves two sperm cells; one fertilizes the egg cell to
form the zygote, while the other fuses with the two polar nuclei that form the endosperm.
After fertilization, the fertilized ovule forms the seed while the tissues of the ovary become
the fruit. In the first stage of embryonic development, the zygote divides to form two cells;
one will develop into a suspensor, while the other gives rise to a proembryo. In the second
stage of embryonic development (in eudicots), the developing embryo has a heart shape
due to the presence of cotyledons. As the embryo grows, it begins to bend as it fills the
seed; at this point, the seed is ready for dispersal. In angiosperms, the process of seed
production begins with double fertilization while in gymnosperms it does not. In both
monocots and dicots, food reserves are stored in the endosperm; however, in non-
endospermic dicots, the cotyledons act as the storage. In a seed, the embryo consists of
three main parts: the plumule, the radicle, and the hypocotyl. In dicots, the hypocotyls
extend above ground, giving rise to the stem of the plant, while in monocots, they remain
below ground. In dicot seeds, the radicle grows downwards to form the tap root while
lateral roots branch off to all sides, producing a dicot tap root system; in contrast, the end
of germination in monocot seeds is marked by the production of a fibrous root system
where adventitious roots emerge from the stem. Seed germination is dependent on seed
size and whether favorable conditions are present. The means by which seeds are
dispersed depend on a seed’s structure, composition, and size. Seeds dispersed by water
are found in light and buoyant fruits, while those dispersed by wind may have specialized
wing-like appendages. Animals can disperse seeds by excreting or burying them; other
fruits have structures, such as hooks, that attach themselves to animals’ fur. Humans also
play a role as dispersers by moving fruit to new places and discarding the inedible portions
containing the seeds. Some seeds can remain dormant and germinate when favorable
conditions arise.

PLANTS NUTRITION AND TRANSPORT

Unlike animals plants obtain their nutrition from the soil and atmosphere. Using
sunlight as an energy source, plants can make all the organic macromolecules they need
by modifications of the sugars they form by photosynthesis. However, plants must take
up various minerals through their root systems for use. Carbon, Hydrogen, and Oxygen
are considered the essential elements. Nitrogen, Potassium, and Phosphorous are
obtained from the soil and are the primary macronutrients. Calcium, Magnesium, and
Sulfur are the secondary macronutrients needed in lesser quantity. The micronutrients,
needed in very small quantities and toxic in large quantities, include Iron, Manganese,
Copper, Zinc, Boron, and Chlorine. A complete fertilizer provides all three primary
macronutrients and some of the secondary and micronutrients. The label of the fertilizer
will list numbers, for example 5-10-5, which refer to the percent by weight of the primary
macronutrients. Soil is weathered, decomposed rock and mineral (geological) fragments

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mixed with air and water. Fertile soil contains the nutrients in a readily available form that
plants require for growth. The roots of the plant act as miners moving through the soil and
bringing needed minerals into the plant roots. Plants use these minerals in: (a) structural
components in carbohydrates and proteins; (b) organic molecules used in metabolism,
such as the Magnesium in chlorophyll and the Phosphorous found in ATP; (c) enzyme
activators like potassium, which activates possibly fifty enzymes; and (d) Maintaining
osmotic balance. Plants need nitrogen for many important biological molecules including
nucleotides and proteins. However, the nitrogen in the atmosphere is not in a form that
plants can utilize. Many plants have a symbiotic relationship with bacteria growing in their
roots: organic nitrogen as rent for space to live. These plants tend to have root nodules
in which the nitrogen-fixing bacteria live. Animals have a circulatory system that transports
fluids, chemicals, and nutrients around within the animal body. Some plants have an
analogous system: the vascular system in vascular plants; trumpet hyphae in
bryophytes. Root hairs are thin-walled extensions of the epidermal cells in roots. They
provide increased surface area and thus more efficient absorption of water and minerals.
Water and dissolved mineral nutrients enter the plant via two routes. Water and selected
solutes pass through only the cell membrane of the epidermis of the root hair and then
through plasmodesmata on every cell until they reach the xylem: intracellular route
(apoplastic). Water and solutes enter the cell wall of the root hair and pass between the
wall and plasma membrane until the encounter the endodermis, a layer of cells that they
must pass through to enter the xylem: extracellular route (symplastic). The endodermis
has a strip of water-proof material (containing suberin) known as the Casparian strip
that forces water through the endodermal cell and in such a way regulates the amount of
water getting to the xylem. Only when water concentrations inside the endodermal cell
fall below that of the cortex parenchyma cells does water flow into the endodermis and
on into the xylem. Xylem is the water transporting tissue in plants that is dead when it
reaches functional maturity. Tracheids are long, tapered cells of xylem that have end
plates on the cells that contain a great many crossbars. Tracheid walls are festooned with
pits. Vessels, an improved form of tracheid, have no (or very few) obstructions
(crossbars) on the top or bottom of the cell. The functional diameter of vessels is greater
than that of tracheids. Water is pulled up the xylem by the force of transpiration, water
loss from leaves. Mature corn plants can each transpirour gallons of water per week.
Transpiration rates in arid-region plants can be even higher. Water molecules are
hydrogen bonded to each other. Water lost from the leaves causes diffusion of additional
water molecules out of the leaf vein xylem, creating a tug on water molecules along the
water columns within the xylem. This "tug" causes water molecules to rise up from the
roots to eventually the leaves. The loss of water from the root xylem allows additional
water to pass through the endodermis into the root xylem. Cohesion is the ability of

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molecules of the same kind to
stick together. Water
molecules are polar, having
slight positive and negative
sides, which causes their
cohesion. Inside the xylem,
water molecules are in a long
chain extending from the roots
to the leaves. Adhesion is the
tendency of molecules of
different kinds to stick
together. Water sticks to the
cellulose molecules in the
walls of the xylem,
counteracting the force of
gravity and aiding the rise of
water within the xylem.
Transpiration exerts a pull on
the water column within the
Figure 1b: Cohesion-Tension Theory
xylem. The lost water Source: https://www.semanticscholar.org/paper/Sap-flow-and-sutransport-in-plants-
molecules are replaced by Jensen-Berg-
water from the xylem of the
leaf veins, causing a tug on water in the xylem. Adhesion of water to the cell walls of the
xylem facilitates movement of water upward within the xylem. This combination of
cohesive and adhesive forces is referred to as the Cohesion-Adhesion Theory.
CONTROL SYSTEM IN PLANTS
At every stage in the life of a plant, sensitivity to the environment and coordination
of responses are evident. One part of a plant can sends signals to other parts. Plants can
sense gravity and the direction of light. A plant’s morphology and physiology are
constantly tuned to its variable surroundings by complex interactions between
environmental stimuli and internal signals. At the organismal level, plants and animals
respond to environmental stimuli by very different means.

Animals, being mobile, respond mainly by behavioral mechanisms, moving toward

positive stimuli and away from negative stimuli. In order for an internal or external stimulus
to elicit a physiological response, certain cells in the organism must possess an
appropriate receptor, a molecule that is sensitive to and affected by the specific stimulus.
Upon receiving a stimulus, a receptor initiates a specific series of biochemical steps, a
signal transduction pathway. This couples reception of the stimulus to the response of the
organism. Plants are sensitive to a wide range of internal and external stimuli.
Plants may not move, but that does not mean they don't respond to their
environment. Plants can sense gravity, light, touch, and seasonal changes. For example,
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you might have noticed how
a house plant bends toward
a bright window. Plants can
sense and then grow toward
the source of light. Scientists
say that plants are able to
respond to "stimuli," or
something—usually in the
environment—that results in
a response. For instance,
light is the stimulus, and the
Figure 1c: Control System of Plants. Source: https://slideplayer.com/slide/7999496/
plant moving toward the light
is the "response."
Hormones are special chemical messengers molecules that help organisms,
including plants, respond to stimuli in their environment. For plants to respond to the
environment, their cells must be able to communicate with other cells. Hormones send
messages between the cells. Animals, like humans, also have hormones, such as
testosterone or estrogen, to carry messages from cell to cell. In both plants and animals,
hormones travel from cell to cell in response to a stimulus; they also activate a specific
response.

HORMONES FUNCTION
Ethylene Fruit ripening and abscission
Gibberellins Break the dormancy of seeds and buds; promote
growth
Cytokinins Promote cell division; prevent senescence
Abscisic Acid Close the stomata; maintain dormancy
Auxins Involved in tropisms and apical dominance

What’s More
Activity 1: Word Pool
Directions: Supply the missing words in each sentence. Choose your answer inside the
banner below.

1. In flowering plants, _________________ stores food that supports flower and fruit
production.
2. ________________ are extensions of individual dermal cells on the root surface.
3. _________________________is the most advantageous of the two types of pollination since it
provides species with greater genetic diversity.
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 4. The presence of a _______________ is responsible for inhibiting the growth of
axillary buds.
5. _________________ are the main photosynthetic organs of most plants.
6. Plant taxonomists use ___________________ leaf shape, spatial arrangement of
leaves and others to classify it.
7. A ____________ is an organ that anchors a vascular plant in the soil.
8. An _______________________ are aboveground from stem or even from leaves.

root root hairs leaves taproot

floral morphology cross-pollination

lateral bud axillary bud adventitious root

What I Have Learned

Explain the process of double fertilization. Use the diagram below.

______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________

What I Can Do
When you climb to places of higher altitudes, the gases that make up the atmosphere,
including oxygen become thinner. When people living close to sea level visit a place with
an altitude of more or less 2000 meters, they sometime experience shortness of breath,
nausea, fatigue and even blackouts. How then do people that live in the Andes or
Himalayas at more than 2000 meters cope with the environment? Explain your answer.

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 Module 2 Animal Reproduction, Nutrition, Digestion and Respiration

Most Essential Learning Competencies

• Compare and contrast the following processes in animal: reproduction
methods, nutrition and digestion and respiration. (STEM_BIO11/12-IVi-J-1)

What’s In
Animals vary in structure and function. An organism has a distinct body plan that limits its
size and shape. This module focuses on reproduction, nutrition and digestions, and
respiration.
REPRODUCTION METHODS
The process by which organisms replicate themselves is called Reproduction. It is
an essential characteristic of life to provide continued existence of species. Animals
produce offspring through sexual and/or asexual reproduction. The reproduction involving
the union of gametes is called Sexual Reproduction. It is an important source of genetic
variation. It is the combination of (usually haploid) reproductive cells from two individuals
to form a third (usually diploid) unique offspring. Sexual reproduction produces offspring
that are usually novel combination of genes. Species that reproduce sexually must
maintain two different types of individuals, males and females, which can limit the ability
to colonize new habitats as both sexes must be present. As humans, we are used to think
of animals as having two separate sexes—male and female—determined at conception.
In the animal kingdom, there are many variations on this theme.

Hermaphroditism occur commonly in lower invertebrates in which one individual

has a functional male and female reproductive parts Hermaphrodites like snail (fig1) may
self-fertilize or may mate with another of their species. When two individual mates. They
can produce up to one hundred
eggs each. Other examples of
hermaphrodites are earthworms,
slugs, tapeworm, barnacles and
clams in which self – fertilization is
common because they have
limited mobility.
Different forms of animals
have different sexual reproductive
strategies . For example corals,
Figure 1 Source: https://courses.lumenlearning.com/wmbiology2/chapter
sponges and some fish release /sexual-reproduction

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sperm and eggs into the water. The eggs are fertilized and transform into larvae which
settle down. Amphibians like frogs form male-female pairs and simultaneously release
eggs and sperm into the water. Many amphibians have specialized ways to take care of
their young. Birds and reptiles rely on internal fertilization so the female lays fertilized
eggs. Mammals rely on internal fertilization and give birth to live offspring. Social insects
such as ants and bees rely on the queen whose primary purpose is reproduction as the
core of the colony. A single individual can produce offspring asexually and large number
of offspring can be produced quickly. Any reproductive process that does not involve
neiosis or the union of nuclei, sex cells, or sex organs is called Asexual Reproduction
(Fig.2). It produces offspring that are genetically identical to the parent because the
offspring are all cloned of the original. There are different ways that animal can reproduce
asexually.Some organisms undergo a process called Fission (also called Binary
Fission). In prokaryotic microorganisms and in some multi-cellular invertebrates, an
organisms splits into two separate organisms after a period of growth. Some unicellular
eukaryotic microorganisms undergo binary fission by mitosis wherein a part of an
individual separates and form a second individual. Many asteroid echinoderm, some sea
naemone and coral polyps reproduce through fission

Coral and Hydra reproduce asexually through Budding. This result from the
outgrowth of a part of a cell or body region resulting to a separation from the original
organisms into two new individuals. Sea stars reproduce asexually by Fragmentation. It
is process wherein body breaks into two parts with sunsequent regeneration. Another
ways of asexual reproduction is Parthenogenesis in invertebrates such as aphids,
wasps, bees where an egg develops into a complete individual without being fertilized.

Fission in Coral polyps Budding in hydra Fragmentation in Sea star

Fig. 2 Asexual Reproduction Methods (https://louis.oercommons.org/courseware/module/822/student/?task=2)

NUTRITION AND DIGESTION

Your body needs nourishment in order to be healthy. The process of digestion breaks
down food you eat in the form that can be used by your body. The blood vessel that
surround the section of your small intestine carry the nutrients from the food you eat to all
parts of your body The main classes of nutrients are carbohydrates, fats, proteins,
water,vitamins and minerals. Carbohydrates supply the body’s main source of energy.

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Fats provide energy that can be released slowly in the body. Protein provide material for
growth and repair worn or injured cells and for growth of new cells. Protein can also
provide energy and can be changed to fat for storage. Water helps control body
temperature and transport materials through the body. Minerals help regulate the body’s
activities. Vitamins can promote growth, release energy from food and assure proper
development of new cells. A calorie is the energy needed to heat one kilogram of water
one degree Celsius.
Digestion breaks large molecules into smaller molecules. Digestive enzymes
are chemicals that help break apart large molecules into nutrients.
Animals have evolved different types of digestive system to breakdown different food they
consume. Gastrovascular cavity, as shown in Figure 3, is found in organisms with one
opening for digestion. Platyhelminthes (flatworms and Cnidaria (coral, jelly fish, and sea
anemones use this type of digestion. Others, like endoparasites, absorbs nutrients
through their external coverings.

Figure 3 Source: (https://tophat.com/marketplace/science-&-

math/biology/textbooks/oer-openstax-biology-openstax-
content/79/4137/)

Digestion includes breakingfood into small parts, liquifying food, digesting food,
helping nutrients pass into the blood streams, absorbing water, and removing wastes.
Figure 4 summarizes digestion of carbohydrates, proteins, and lipids in the body. The
mouth and the stomach breaks down food mechanically and begin chemical digestion.
In the small intestine, nutrientas are absorbed through villi. Water is then absorbed in the
intestine. The mouth and the stomach break down food mechanically and begin chemical
digestion. In the small intestine, nutrients are absorbed through villi. Water is then
absorbed in the intestine. Animal diet need carbohydrates, protein and fat as well as
vitamins and inorganic components for nutritional balance. Vitamins differ from one
animal to another. This is because some animals can synthesize what others cannot such

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as vitamin C. Many primates cannot synthesize ascorbic acid so it is considered a vitamin
while other animals especially carnivore can make their own.

Figure 4 Source: (https://tophat.com/marketplace/science-&-

math/biology/textbooks/oer-openstax-biology-openstax-content/79/4137/)

RESPIRATION is the process of taking in oxygen into cells using it in releasing

energy by burning food then eliminating waste materials like carbon dioxide and water
from the body. Different forms of life have devised different means of obtaining oxygen
from the surrounding atmosphere. Gas exchange during respiration occurs through
diffusion. It is a process in which transport is driven by a concentration gradient. Diffusion
is a slow passive transport process. The environment in which the animals lives greatly
determine how an animal respire. Organisms like cnidarian and flatworms kept their cell
moist and gases diffuse quickly via direct diffusion. Figure 5 shows the process of
respiration in flatworms by diffusion across the outer membrane. Earthworms and
amphibians use their skin for respiration. Gills are also found in mollusks and
crustaceans. Aquatic animals allow it to obtain oxygen from water. Insects have openings
called spiracles. It also have a specialized tracheal system for respiration.

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Figure 5 Source: (https://tophat.com/marketplace/science-&-math/biology/textbooks/oer)-)openstax-
biology-openstax-content/79/4142/

RESPIRATION IN HUMAN
In human, air enters the respiratory system through the nasal cavity and
pharynx and then passes through the trachea and into the bronchi which bring air
into the lungs. Gas exchange takes place in the alveoli and in the capillaries that
envelop them (Figure 6).

Figure 6 Source: (https://tophat.com/marketplace/science-&-math/biology/textbooks/oer-

openstax-biology-openstax-content/79/4137/)

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BOYLE’S LAW AND THE BREATHING PROCESS

Figure 7 Source: (https://tophat.com/marketplace/science-&-math/biology/textbooks/oer-openstax-biology-openstax-

content/79/4137/)

Breathing process involves inhalation and exhalation. The mechanics of

breathing can be explained using the relationship between gas pressure and volume.
According to Boyle, volume and pressure are inversely related. If a volume of a
confined gas decreases, pressure increases or vice versa. During inhalation, volume
increases as a result of contraction of the diaphragm, and pressure decreases. As a
result, air rushes into the respiratory system. Upon exhalation, the lungs recoil and
force the air out of the lungs and the intercostal muscle relax, returning the chest wall
back to its original position. The diaphragm also relaxes and moves into the thoracic
cavity. The increase in pressure within the thoracic cavity relative to the environment
cause the air to rush out of the lungs.

What’s More

Activity 1: Deepening
Why is reproduction needed? What happens when a population stops
reproducing?
_____________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________

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Activity 2. integration

Animal Nutrition Whether for conservation, research, veterinary medicine, or

agriculture, a well-balanced diet is essential. A researcher may develop a new diet based
on the food of an animal in its native environment. Cats and dogs, for example, are
carnivores, yet most commercial dog and cat foods contain grains and vegetables, which
supply carbohydrates. How do nutrients affect animals?
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________

Activity 3. Processing and Generalizing

What is the importance of the respiratory system? Why is it needed by many animal phyla?

__________________________________________________________________________________
__________________________________________________________________________________

What I Have Learned

Create a concept strip to summarize your learnings in this module. Use a separate
sheet of paper.

What I Can Do

Nutrition is defined as the process of obtaining and delivering the food

needed for health and growth. Examine your meals, whether at home or at a favorite
restaurant. Include photos. Write a food review.

FOOD REVIEW

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 Module 3 Circulation and Immune System

Most Essential Learning Competencies

• Compare and contrast the following processes in plants and animals:
reproduction, development, nutrition, gas exchange, transport/circulation,
regulation of body fluids, chemical and nervous control, immune systems, and
sensory and motor mechanisms.

What’s In

Organisms require a mechanism for efficient transporting of nutrients and

removal of waste products throughout their body. The circulatory system has evolved
over time, from simple diffusion through cells to a complex network of blood vessels
that reach all parts of the organism.
Numerous pathogens exist in the environment in the form of viruses, bacteria,
and other infectious organisms. The immune system searches the body for signs of
these pathogens and initiate specific responses that are essential for survival. In this
module, you will learn more on the transport, circulation and immunity in animal organ
systems.

Circulatory System

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A circulatory system has three main features: circulatory fluid (blood or hemolymph)
that transports materials, a set of blood vessels, and a heart to pump fluid through the
vessels.

Source:https://lh3.ggpht.com/E_CZiP8ZXY/URy3YTJZDpI/AAAAAAAAEFc/FawPDPGfxw8/Open%252520and%252
520Closed%252520circulatory%252520system_thumb%25255B7%25255D.gif?imgmax=800

Types of circulatory system

1. Open circulatory system – the circulatory fluid, called hemolymph bathes body
cells. The hemolymph is not enclosed in blood vessels but is pumped into a cavity
called a hemocoel. As the heart pumps and the animal moves, the hemolymph is
pushed into the organs through openings and pulled back through holes called
ostia. Arthropods, such as grasshoppers, and some molluscs, including clams,
have open circulatory systems.

2. Closed circulatory system – a circulatory fluid called blood is confined to vessels

and is distinct from the interstitial fluid. Blood is contained in the blood vessels
and circulates unidirectionally from the heart/s to the organs and back to the
heart. Chemical exchange occurs between the blood and the interstitial fluid, as
well as between the interstitial fluid and body cells. Annelids, cephalopods, and all
vertebrates have closed circulatory system.

Blood vessels are classified into three main types: arteries, capillaries, and veins.
Arteries carry blood away from the heart to organs throughout the body. Arteries
branch into arterioles and then to capillaries. Capillaries are microscopic vessels with
thin and porous walls where gases and other chemicals are exchanged via simple
diffusion. Capillaries converge into venules, and venules converge into veins which
carry blood back towards the heart.

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 The hearts of vertebrates are composed of two or more muscular chambers.
Chambers that receive blood entering the heart are called atria (atrium, singular) while
those that pump blood are called ventricles (ventricle, singular).

Circulation in vertebrates has evolved to promote efficiency of transport and

exchange of nutrients and waste materials. In fishes, the heart has two chambers: one
atrium and one ventricle. Blood flows through one circuit or single circulation. It picks
up oxygen in the capillary beds of the gills and delivers it to capillary beds in all body
tissues. Oxygen-poor blood then returns to the heart. However, amphibians, reptiles
and mammals utilize double circulation, where blood flows along two partially
separated circuits. In amphibians, the heart has three chambers: two atria and one
ventricle. The force of one contraction pumps blood from the heart to the lungs and
back. The force of a second contraction pumps blood from the heart to all body tissues
and back to the heart. In birds and mammals, the heart has four chambers: two atria
and two ventricles. The blood flows through two fully separated circuits. In one circuit,
blood flows from the heart to the lungs and back. In the second circuit, blood flows from
the heart to all body tissues and back.
Each half pumps blood in a separate circuit:

• Pulmonary circuit: Blood flows from right half of heart, to lungs (gains oxygen),
to left half of heart
• Systemic circuit: Blood flows from left half of heart, to body (loses oxygen), to
right half of heart

Amphibians are capable of gas exchange in their skin and lungs, hence the
pulmocutaneous circuit.

19
 Source: https://image.slidesharecdn.com/34lecturepresentation-160502161716/95/biology-in-focus-chapter-34-19-
638.jpg?cb=1462205875

Path of blood flow in the heart (mammalian)

• The heart receives blood (low in oxygen) from the body into the right atrium
through the superior and inferior vena cava (end of systemic circuit)
• Right atrium sends blood to the right ventricle
• Right ventricle sends blood to the pulmonary trunk that leads to the lungs (start
of pulmonary circuit)
• Pulmonary veins empty blood from the lungs into the left atrium (end of
pulmonary circuit). Blood is now high in oxygen.
• Left atrium sends blood to left ventricle.
• Left ventricle sends blood out of the heart into the aorta to be distributed
throughout the body (start of systemic circuit)

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 Source: https://moosmosis.files.wordpress.com/2016/06/2000pxdiagram_of_the_
human_heart_cropped-svg.png

Immune System

The immune system acts as a defense system against microbes, growth of

tumor cells and maintains homeostasis by the destruction or removal of abnormal or
dead cells. A properly functioning immune system is capable of distinguishing a
pathogen from its normal cells. This is accomplished when cells of the immune system
are able to recognize and bind to pathogens and activate defense responses. There
are two types of immune defenses among animals: innate immunity and adaptive
immunity.

Innate immunity or non-adaptive immunity is the body’s first line of immune

response. It allows the body to respond quickly to any pathogen whether they have
been previously encountered or not. It relies on mechanisms that exist before an
infection. Innate immune response is non-specific which means that the same cells
respond to a range of pathogens. It has no memory, so the same response is repeated
after exposure. The internal and external defenses of innate immunity is the same for
any pathogen that could be a threat to the body. External defenses that are part of
innate immunity include the skin, mucous membranes and various secretions of the
body. Mucus traps pathogens and other foreign particles. These secretions also inhibit
bacterial and fungal growth. If a pathogen penetrates the external defenses, the
internal defenses are triggered which include phagocytic cells engulfing foreign bodies
(neutrophils, natural killer cells, eosinophils, basophils, mast cells,

21
macrophages), production of antimicrobial proteins, and promotion of
inflammatory responses of the body. Such responses occur rapidly and may be
observed within minutes.

Source:https://slideplayer.com/slide/13895677/85/images/2/Animal+Immunity+INNATE+IMMUNITY+Barri
er+defenses%3A+Internal+defenses%3A.jpg

Adaptive immunity, also known as acquired immune response is the body’s

second line of defense. It is based on resistance acquired during the organism’s
lifetime which explains why you develop immunity to a disease after being infected with
it. It has much slower response compared to innate immunity but is more specific, with
each cell responding to a particular antigen. Adaptive immunity relies on lymphocytes
(T cells and B cells) which are WBC capable of recognizing and binding to a specific
antigen via the antigen receptor. A single B or T cell may have about 100,000 antigen
receptors on its surface, displaying specificity. Cytotoxic T Lymphocytes (CTLs)
eliminate infected cells, including the pathogen. Helper T cells activate other T cells
and B cells. B cells are lymphocytes that are capable of producing antigen-specific
antibodies.

22
 Antibodies recognize and bind their antigen. When enough antibodies attach to a
pathogen, they can completely coat it and block it from interacting with the body's cells.
Antibodies also serve as a label or tag, sending a signal to phagocytic cells. Aside from
marking pathogens for phagocytosis, they can also cause pathogens to clump
together, making it easier for neutrophils and macrophages to deal with them in groups
than one by one.

What’s More

Activity 1: What am I for?

Fill out the table with the description of the structure and function of each item.

Structure Function

heart

blood vessel

artery

vein

hemolymph

blood

capillary

23
Activity 2: Types of immunity

Directions: Write the type of immunity being described in each statement.

_______________________1. It can occur from exposure to an infection, wherein
a person gets a disease and develops immunity as a
result.
_______________________2. It develops from immunological memory.
_______________________3. It occurs from vaccination wherein the vaccine
mimics a particular disease, causing an immune
response in the vaccinated individual without getting
them ill.
_______________________4. It can respond quickly to defend against any
pathogen.
_______________________5. General protection that a person is born with.
_______________________6. It includes the body’s first line of immune response
_______________________7. The ability of the immune system to respond to
unknown threats.
_______________________8. It has a slower but more specific immune response.
_______________________9. Non specific immunity.
_______________________10. The immune response to a specific pathogen that
can be reactivated if the pathogen is ever encountered
again.

What I Have Learned

Fill out the below.

What part of the topic did you like? What part of the topic didn’t you like?

What was easy? What was hard?

What I Can Do

Immunization through vaccines is a global success story in the health sector.

How do vaccines work? Explain your answer.

24
 Module 4 Nervous Control, Sensory and Motor Mechanisms

Most Essential Learning Competencies

• Compare and contrast the following processes in plants and animals:
reproduction, development, nutrition, gas exchange, transport/circulation,
regulation of body fluids, chemical and nervous control, immune systems, and
sensory and motor mechanisms.

What’s In
NERVOUS SYSTEM
The nervous system is responsible for controlling much of the body, both through
somatic (voluntary) and autonomic (involuntary) functions. The ability to sense and
react originated billions of years ago in prokaryotes, enhancing survival and
reproductive success in changing environments. By the time of the Cambrian explosion
more than 500 million years ago, specialized systems of neurons had appeared that
enable animals to sense their surroundings and respond rapidly. Invertebrate nervous
systems range in complexity from simple nerve nets to highly centralized nervous
systems having complicated brains and ventral nerve cords.

Source: CAMPBELL BIOLOGY IN FOCUS © 2014 Pearson Education, Inc. Urry • Cain • Wasserman • Minorsky •
Jackson • Reece Lecture Presentations by Kathleen Fitzpatrick and Nicole Tunbridge 38 Nervous and Sensory Systems

Most of neuron’s organelles, including its nucleus are in the cell body. Most neurons
have branched extensions called dendrites (from Greek, tree) that receive signals
from other neurons and an axon that transmits signals to other cells. The cone shaped
base of an axon, called the axon hillock is typically where signals that travel down the
axon are generated. The axon divides into branches and each branched end transmit
information to another cell at a junction called synapse. The part of each axon branch
that forms this specialized junction is a synaptic terminal. At most synapses, chemical
messengers called neurotransmitters pass information from the transmitting neuron

25
to the receiving cell. Neurons rely on glial cells or glia for functions that include
nourishment, insulation, and regulation. In vertebrates, the central nervous system
(CNS), consisting of the brain and the spinal cord, integrates information, while the
nerves of the peripheral nervous system (PNS) transmit sensory and motor signals
between the CNS and the rest of the body. A central nervous system (CNS) and a
peripheral nervous system (PNS) process information in three stages: sensory input,
integration, and motor output to effector cells. The simplest circuits control reflex
responses, in which sensory input is linked to motor output without involvement of the
brain. More complex invertebrates, such as segmented worms and arthropods have
many more neurons. Their behavior is regulated by more complicated brains and by
ventral nerve cords containing ganglia, segmentally arranged cluster of neurons.
Afferent neurons carry sensory signals to the CNS. Efferent neurons function in
either the motor system, which carries signals to skeletal muscles, or the autonomic
nervous system, which regulates smooth and cardiac muscles. The sympathetic and
parasympathetic divisions of the autonomic nervous system have opposite effects on
a diverse set of target organs. Activation of the sympathetic division corresponds to
arousal and energy generation (the “fight-or-flight” response). For example, the heart
beats faster, digestion is inhibited, the liver converts glycogen to glucose, and the
adrenal medulla increases secretion of epinephrine (adrenaline). Activation of the
parasympathetic division generally causes opposite responses that promote calming
and a return to self-maintenance functions (“rest and digest”). Thus, heart rate
decreases, digestion is enhanced, and glycogen production increases. The enteric
division controls the activity of many digestive organs.

Source: CAMPBELL BIOLOGY IN FOCUS © 2014 Pearson Education, Inc. Urry • Cain • Wasserman •
Minorsky • Jackson • Reece Lecture Presentations by Kathleen Fitzpatrick and Nicole Tunbridge 38
Nervous and Sensory Systems

26
 The cerebrum has two hemispheres, each of which consists of cortical gray
matter overlying white matter and basal nuclei. The basal nuclei are important in
planning and learning movements. The pons and medulla oblongata are relay stations
for information traveling between the PNS and the cerebrum. The reticular formation,
a network of neurons within the brainstem, regulates sleep and arousal. The
cerebellum helps coordinate motor, perceptual, and cognitive functions. The thalamus
is the main center through which sensory information passes to the cerebrum. The
hypothalamus regulates homeostasis and basic survival behaviors. Within the
hypothalamus, a group of neurons called the suprachiasmatic nucleus (SCN) acts as
the pacemaker for circadian rhythms. The amygdala plays a key role in recognizing
and recalling a number of emotions.

Source: CAMPBELL BIOLOGY IN FOCUS © 2014 Pearson Education, Inc. Urry • Cain • Wasserman •
Minorsky • Jackson • Reece Lecture Presentations by Kathleen Fitzpatrick and Nicole Tunbridge 38 Nervous
and Sensory Systems

Each side of the cerebral cortex has four lobes—frontal, temporal, occipital, and
parietal—that contain primary sensory areas and association areas. Association areas
integrate information from different sensory areas. Broca’s area and Wernicke’s area
are essential for generating and understanding language. These functions are
concentrated in the left cerebral hemisphere, as are math and logic operations. The
right hemisphere appears to be stronger at pattern recognition and nonverbal thinking.

In the adult, reshaping of the nervous system can involve the loss or addition of
synapses or the strengthening or weakening of signaling at synapses. This capacity
for remodeling is termed neuronal plasticity. Short-term memory relies on temporary
links in the hippocampus. In long-term memory, these temporary links are replaced by
connections within the cerebral cortex. Alzheimer’s disease and Parkinson’s disease

27
are neurodegenerative and typically age related. Alzheimer’s disease is a dementia in
which neurofibrillary tangles and amyloid plaques form in the brain. Parkinson’s
disease is a motor disorder caused by the death of dopamine-secreting neurons and
associated with the presence of protein aggregates.

Source: CAMPBELL BIOLOGY IN FOCUS © 2014 Pearson Education, Inc. Urry • Cain • Wasserman • Minorsky •
Jackson • Reece Lecture Presentations by Kathleen Fitzpatrick and Nicole Tunbridge 38 Nervous and Sensory
Systems

SENSES

The detection of a stimulus precedes sensory transduction, the change in the

membrane potential of a sensory receptor in response to a stimulus. The resulting
receptor potential controls transmission of action potentials to the CNS, where sensory
information is integrated to generate perceptions. The frequency of action potentials in
an axon and the number of axons activated determine stimulus strength. The identity
of the axon carrying the signal encodes the nature or quality of the stimulus.
Mechanoreceptors respond to stimuli such as pressure, touch, stretch, motion, and
sound. Chemoreceptors detect either total solute concentrations or specific molecules.
Electromagnetic receptors detect different forms of electromagnetic radiation.
Thermoreceptors signal surface and core temperatures of the body. Pain is detected
by a group of nociceptors that respond to excess heat, pressure, or specific classes
of chemicals.

Most invertebrates sense their orientation with respect to gravity by means of

statocysts. Specialized hair cells form the basis for hearing and balance in mammals
and for detection of water movement in fishes and aquatic amphibians. In mammals,
the tympanic membrane (eardrum) transmits sound waves to bones of the middle

28
ear, which transmit the waves through the oval window to the fluid in the coiled cochlea
of the inner ear. Pressure waves in the fluid vibrate the basilar membrane, depolarizing
hair cells and triggering action potentials that travel via the auditory nerve to the brain.
Receptors in the inner ear function in balance and equilibrium.

Invertebrates have varied light detectors, including simple light sensitive

eyespots, image-forming compound eyes, and single lens eyes. In the vertebrate eye,
a single lens is used to focus light on photoreceptors in the retina. Both rods and
cones contain a pigment, retinal, bonded to a protein (opsin). Absorption of light by
retinal triggers a signal transduction pathway that hyperpolarizes the photoreceptors,
causing them to release less neurotransmitter. Synapses transmit information from
photoreceptors to cells that integrate information and convey it to the brain along axons
that form the optic nerve.
Taste (gustation) and smell (olfaction) depend on stimulation of chemoreceptors
by small dissolved molecules. In humans, sensory cells in taste buds express a
receptor type specific for one of the five taste perceptions: sweet, sour, salty, bitter,
and umami (elicited by glutamate). Olfactory receptor cells line the upper part of the
nasal cavity. More than 1,000 genes code for membrane proteins that bind to specific
classes of odorants, and each receptor cell appears to express only one of those
genes.

MOVEMENT AND LOCOMOTION

Source: CAMPBELL BIOLOGY IN FOCUS © 2014 Pearson Education, Inc. Urry • Cain • Wasserman •
Minorsky • Jackson • Reece Lecture Presentations by Kathleen Fitzpatrick and Nicole Tunbridge 39 Motor
Mechanisms and Behavior

The muscle cells (fibers) of vertebrate skeletal muscle contain myofibrils

composed of thin filaments of (mostly) actin and thick filaments of myosin. These
filaments are organized into repeating units called sarcomeres. Myosin heads,
energized by the hydrolysis of ATP, bind to the thin filaments, form cross-bridges, and

29
then release upon binding ATP anew. As this cycle repeats, the thick and thin filaments
slide past each other, shortening the sarcomere and contracting the muscle fiber.

Skeletal muscles, often in antagonistic pairs, contract and pull against the
skeleton. Skeletons may be hydrostatic and maintained by fluid pressure, as in worms;
hardened into exoskeletons, as in insects; or in the form of endoskeletons, as in
vertebrates. Each form of locomotion—swimming, movement on land, or flying—
presents a particular challenge. For example, swimmers need to overcome friction, but
face less of a challenge from gravity than do animals that move on land or fly.

What’s More
Activity 1: Brain Check
I. Label the parts of the brain.

1.___________

2.___________

3.___________

4.___________

5.___________

6.___________

7.___________

8.___________

II. Identify what part of the brain is responsible for the given functions.
____________1. The brain part controls thinking
____________2. This brain part controls balance, movement, and coordination
____________3. This brain part controls involuntary actions such as breathing, heartbeats, and
digestion.
____________4. This part of the nervous system moves messages between the brain and the
body.
____________5. This part of the cerebrum interprets and sorts information from the senses

30
____________6. This part of the cerebrum processes messages from the eyes
____________7. This part of the cerebrum helps us with speech and hearing and language
____________8. This part of the cerebrum helps us make decisions and solve problems

What I Have Learned

Draw a concept map of what you have learned in this module.

What I Can Do
Why can eating “hot” peppers cause a person to sweat?

___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________

31
 32
MODULE 1 MODULE 2
Activity 1 Reproduction is a crucial survival strategy that
Activity 1 ensures the survival of a species. As a result, life would
1. Taproot cease to exist if reproduction did not occur. Higher
species (such as humans) reproduce sexually, whereas
2. Root hair
lesser, unicellular organisms reproduce asexually.
3. Cross-pollination (Answer may vary)
4. Lateral bud
5. Leaves
6. Floral morphology Activity 2: Food nutrients are used as the primary
7. Root energy source by animals through a variety of processes
8. Adventitious root such as digestion and absorption in the digestive system,
blood transport, and cell metabolism. The functioning of
numerous tissues and organs in animals are linked to the
Activity 2 regulation of animal nutrition. (Answer may vary)
9. Endarch
10. nettted Activity 3: Different organisms have evolved different
11. scattered methods of obtaining oxygen from the surrounding
12. multiples of 4 and 5 environment as they progressed along the evolutionary
13. 1 tree. The environment in which an animal lives has a
significant impact on how it breathes. (Answer may vary)
14. 2
What I have learned (answer may vary)
KEY CONCEPTS
• Animals vary in structure and function.
• An organism has a distinct body plan that limits
its size and shape
• The reproductive methods, nourishment and
digestion, and respiration of different
organisms differ.
What I can do: (Answer may vary)
Answer Key
 33
MODULE 3 MODULE 4
Activity 1 Activity 1
1. cerebrum
2. frontal lobe
3. parietal lobe
4. occipital lobe
5. temporal lobe
6. cerebellum
7. brain stem
8. spinal cord
II.
1. cerebrum
2. cerebellum
3. medulla oblongata
4. brain stem
5. parietal lobe
6. occipital lobe
Activity 2 7. temporal lobe
8. frontal lobe
1. Adaptive
2. Adaptive What I Can Do?
3. Adaptive
Student answer may vary
4. Innate
5. Innate
6. Innate
7. Innate
8. Adaptive
9. Innate
10. Adaptive
Activity 3
Answers may vary
Activity 4
Answers may vary
Answer Key